


This precious time when time is new

by JaneBuzJane



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Age Regression/De-Aging, Alpha Felix Fraldarius, Alpha/Beta/Omega Dynamics, Bodily Fluids, Coming In Pants, Creampie, Cunnilingus, De-Aged Felix and Regular-Aged Sylvain fuck, Dead Dove: Do Not Eat, Desperation, Felching, Knotting, M/M, Nipple Play, No Spoilers, Omega Sylvain Gautier, Porn with Feelings, Post-Timeskip | War Phase (Fire Emblem: Three Houses), References to Canonical Character Death, Rutting, Scenting, Vaginal Fingering, Vaginal Sex
Language: English
Status: Completed
Published: 2020-05-08
Updated: 2020-05-08
Packaged: 2021-03-02 21:28:20
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 2,844
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24073702
Author URL: https://archiveofourown.org/users/JaneBuzJane/pseuds/JaneBuzJane
Summary: Felix is de-aged by a mage.... directly into the middle of his first rut.
Relationships: Felix Hugo Fraldarius/Sylvain Jose Gautier
Comments: 7
Kudos: 95
Collections: Omega Sylvain Week





	This precious time when time is new

**Author's Note:**

> PLEASE READ THE TAGS. 
> 
> This fic contains an underage character and an of-age character engaging in consensual, rut-motivated sex. Please navigate away/do not read if this squicks you. 
> 
> Fill for days 5 and 7 of Omega Sylvain Week, respectively: 'Accident' and 'Timing.'
> 
> Endless thanks to [notallbees](https://archiveofourown.org/users/notallbees/pseuds/notallbees) for helping me out whenever I got stuck with this one. 😊 (And for motivating me to finish it in the first place!!)
> 
> Please note: as an omega in this 'verse, Sylvain has a vagina.

"He's _what?_ "

"He's Felix, but younger," Ingrid says, looking grim. "Going from his scent, this is his first rut. How old was he when that happened?"

"Three and ten years," Sylvain says, his head spinning. He looks at Felix's door, semi-amused at the rolling series of growls he can barely hear through the wood. Dimitri shuffles his feet, and Dedue places a hand on his shoulder. Sylvain glances at him.

"Did you try and talk to him?"

"He won't, ah. Let me in. My pheromones..." Dimitri makes a vague gesture, and Sylvain nods.

Out of their whole friend group, he's the only one that presented as an omega. And if Sylvain's memories of pre-Duscur, pre-presentation Felix are correct - and they are - not a single one of his alpha friends are going to be able to get close to him.

A fact which Ingrid, Dimitri, and Dedue clearly know, since they'd fetched him straight from the training yards.

"I can't believe you all would ruin the only honest training I've done in years for this." He'll never let them live it down. They're going to be hearing about this for the rest of their lives.

Dedue clears his throat. "We had no way of knowing when that spell would activate. The mage we captured was very clear that it could happen at any time."

Sylvain ponders this for a moment. "Alright, you've hooked me. But c'mon, guys, what do you actually need me to do? Go in there and feed him, or something?"

Ingrid's cheeks turn pink. Dimitri looks down at the ground. Dedue meets his gaze steadily.

"He won't get through this without someone to help him."

Sylvain feels the earth tilt under him for a brief moment. "You - come again?"

"He's in no danger -"

"He's in some danger!" Dimitri bursts out. "The first time - Glenn helped with scenting -" He falls silent.

It all snaps into place.

"I wasn't there, the first time," Sylvain says slowly. "You think I could... help him? Like that?"

"I don't think you have a choice," Ingraid says. "He wasn't growling like that when this first started. He's getting worse."

"We'll bring you anything you need," Dimitri assures him. "Just... look after him. Guide him through it while we question the mage for a solution."

Sylvain groans. Scrubs at his hair. "If he'll let me."

"He's - his memories are those of a younger Felix," Ingrid says. "He's - well. He asked us for you. In not so many words."

Sylvain feels a pang in his chest and buries it, deep down, because he doesn't want to confront how torn that makes him feel.

"Alright. I guess. But if this goes wrong," he cautions them, "Remember it wasn't my idea."

Dedue nods, taking Sylvain's words to heart, and Ingrid shoves him towards the door. As his hand falls upon the knob, Dimitri grabs his arm, looking him in the eye.

"Thank you, Sylvain. We won't let you down." The hairs on the back of his neck raise at the alpha timbre in Dimitri's voice.

"No problem, your Highness," he says, saluting with his free hand. "But it's Felix you should be worried about."

  


* * *

  


Someone - Sylvain suspects Dedue - has shut the curtain in Felix's room, leaving the room in a dim, murky light. The scent is overwhelming - a raw, acrid version of Felix's normal scent. Sylvain breathes through his mouth as he approaches the huddle of blankets on the bed. "Felix? It's me, Sylvain."

The blankets rustle. "Sylvain? What took you so long?"

Sylvain forces a chuckle. "Why? Worried about me?" A tiny growl from underneath the bedclothes has his heart skipping a beat. 

"Ingrid was here, but she was mean, and Dimitri was..." He trails off. Sylvain can picture the way his nose wrinkles.

"Ah, yeah. He... smells a bit different now, doesn't he?"

Felix pokes his head out, finally. Sylvain is captivated by the sight of a Felix he once knew - his Felix, in perfect miniature. "Mm. Don't like it."

Sylvain chuckles for real this time. "That's the Felix I know." He sits on the edge of the bed, careful to stay away from Felix's makeshift den of blankets. "How are you feeling?"

Felix shrugs. "Hot. Where's Glenn? Why -" He stops and tilts his head. Sylvain is close enough to see his pupils dilate. "You smell different."

"Glenn's... away," Sylvain says vaguely. "Different, huh? Dimitri-different?"

"No, Felix says slowly. He crawls closer, tilting his face towards Sylvain's neck. "Good different." 

Sylvain swallows. "Might be because I'm an omega now. What do you think?" He cocks his head and pulls his collar aside, and Felix licks his lips, eyes flickering from Sylvain's face to his neck.

"Can I?" Despite the question, he's already leaning in, resting a hand on Sylvain's knee and nosing shyly at his neck. Sylvain's heart thuds, and his cunt throbs.

"Yeah, of course. 'S what I'm here for." Felix's nose against his neck sends waves of gooseflesh pebbling down his skin, and Felix whines.

"Sylvain, you - mm - feel nice." His hand shifts higher up Sylvain's thigh and he pushes his face against his neck, shameless in his exploration. 

Sylvain chuckles nervously and shifts under the persistent touch of Felix's hand. "Getting a little close to a dangerous area, there."

Felix takes no notice and scrambles closer, pawing at the front of Sylvain's shirt and straddling his thigh while he huffs Sylvain's neck with determination. Sylvain squirms.

"Okay, yeah - here." He holds Felix back for a brief moment - feeling a moment of wonder at Young Felix's delicate musculature - and strips off his shirt, tossing it across the room. Wrapping an arm around Felix's waist, he guides Felix's head to his neck and closes his eyes. "Better?"

Felix makes a considering noise, sliding his hand up Sylvain's chest and grabbing the back of his neck before rubbing his face against Sylvain's throat. Sylvain gasps, arousal pooling in his stomach. Felix huffs, sifting through his scent. "Feels good. Need more."

He shifts closer and unconsciously shifts his hips against Sylvain's thigh - not grinding, but almost. Throwing a prayer to the Goddess, Sylvain presses his thigh up and gently pushes Felix's shoulders down to encourage him to move. Then, summoning all his courage - this is Felix - he bends down and scents Felix's neck in kind, licking softly. "And now?"

Felix whimpers, shuddering. "Why does it feel like this?" His hips jerk, rutting against Sylvain's thigh. "S-Sylvain."

If this is anything like Sylvain's first heat, Felix has to be scared, worried... probably triple the amounts that Sylvain was, since he's in an unfamiliar place.

"I'm here. You're going to be alright." Steeling himself, Sylvain cups the front of Felix's trousers, feeling out the shape of him. "I've got you." Felix's hips buck into his hand with a keening little moan that has Sylvain shivering.

"Sylvain, oh - good, feels good." Sylvain winces as Felix digs his teeth into his neck, worrying at the join of his neck and shoulder. Nevertheless, it makes his cunt hot, and he tilts his head to the side as his stomach swoops.

He reaches inside Felix's smalls and gently grasps his cock. "If you need to bite me, go ahead." He strokes Felix's cock once, slowly running his thumb along the small, plush head of it.

With a wail, Felix spends in Sylvain's hand. Sylvain inhales reverently: already there's a slight bulge forming at the base of his cock. Not a knot, yet, but it will be, later in the rut. With Felix's head buried in his neck, Sylvain shamelessly takes advantage of the warm weight in his lap, grinding his cunt against Felix's knee until Felix shyly asks him,

"Wha - what're you doing?" 

"What am I doing right now? Or doing here, in general?" Sylvain feels the bob of Felix's throat against his own as he swallows heavily.

"You're -" A flush of pink appears on the back of his neck, but he keeps his nose buried in Sylvain's throat. "You're touching me."

Sylvain pauses. Surely - "Yeah, haven't you ever touched yourself?"

Felix nods. "But _you_ never touch me."

Sylvain blanches. "Um. There are special rules during ruts and heats, so. I'm following those rules instead." He strokes the dewy skin of Felix's back and noses at the top of his head. "I'm doing a good job, right?"

Felix's voice is muffled and shy. "I - I like it." 

"I'll let you in on a secret," Sylvain says, his rational brain screaming at him to slow down. "It can feel even better." He props his chin on the top of Felix's head. "Wanna try?" He can feel it when Felix nods.

"You'll show me?" 

Sylvain squeezes his eyes shut. "Yeah, baby, I will." It slips out; he doesn't mean to say it. His mouth is a little dry. "Have you ever kissed anyone?"

Felix squints. "Why?"

"Because it's fun and it feels good, that's why." Sylvain holds Felix close and eases them down on the bed until Felix is sitting on his lap, hands propped against the headboard, while Sylvain rests on a mound of pillows. Felix’s long, beautiful eyelashes sweep his skin as he glances down at Sylvain’s lips.

"I saw it in a book once." He hesitates, then mashes his mouth against Sylvain's, clumsy and wet.

It's not the best kiss Sylvain's ever had, but it is the most eager. Felix's tongue is in his mouth as soon as Sylvain parts his lips in a gasp.

"Fe - Felix," Sylvain says, panting. Felix looks back at him, eyes bright.

"Is that... not..."

Sylvain shakes his head. "It's perfect." He guides their mouths together again, brushing Felix's tongue with his. Felix keens and grabs at Sylvain's shoulders, anchoring himself, the smell of him heady in the air.

"That's it," Sylvain breathes, licking Felix's bottom lip. "Now you try." Felix nips at Sylvain's lip with an amount of force he wasn't expecting, teeth digging in. Sylvain's back arches, and Felix pulls back, breathing heavily.

"You like it."

"I do, yeah," Sylvain rests his hands on Felix's slight hips. "Do you?"

Felix nods before bending down to kiss him again, slick and open-mouthed.

Wet sounds fill the bubble surrounding them, slowing time as it narrows to nothing but the heat of Felix's mouth against Sylvain's. Felix gives a little snarl when Sylvain playfully bites his tongue, shoving his head back and burying his face in Sylvain's neck again.

"Oh - ah, saints, Felix, that feels good." Felix applies his kissing technique to Sylvain's neck, rolling the skin between his lips and laving at it, and the pulsing in Sylvain's cunt is hard to ignore.

"Syvlain," Felix moans, rubbing his nose against Sylvain's skin. "'M hot." 

Sylvain rucks up the back of Felix's shirt and pulls it over his head, throwing it somewhere near the end of the bed. Felix plasters himself to Sylvain's front and shivers, thighs clamping around Sylvain's hips. For a brief moment, Sylvain can feel the hard line of Felix's cock against his pussy, and his eyes flutter.

As Felix scoots his way back up Sylvain's body for a kiss, Sylvain puts a hand on his chest. Without a shirt, Sylvain can admire the pale, stark lines of his body and the way his collarbones delicately grace his frame. His nipples are pink instead of dusky, like Sylvain's, and his chest is hairless. 

"Ever touched yourself here?" he asks, letting his thumb brush one of them. Felix gasps and shudders, his chin ducking into his chest as he hunches over. Sylvain shushes him, petting it with a firmer touch as he watches Felix quiver. 

"S-Sylvain," Felix gasps. His small cock is fully hard in his smalls now, hips skittering forward to rut against air. Sylvain can see his eyes glazing over, the rut haze fogging over his senses once more. "I need -"

"Yeah," Sylvain murmurs. "Okay. Smalls off, c'mon." They both strip themselves of their remaining clothing until suddenly Sylvain has Felix between his legs, clutching at his arms and nibbling at his neck. Sylvain finds it hard to breathe as Felix's nails dig in, and his neck lolls to the side. He's stinking up the room, he knows, but this is _Felix_ in his lap, grinding against him, cock sliding against his folds -

Felix moans, high and loud, when the head of his cock glances off of Sylvain's cunt. His head shoots up and he tenses, looking down between them. "Sylvain - what -" 

"My cunt," Sylvain says breathlessly. "You can - you can keep doing that. Feels good."

Trembling, Felix rolls his hips again, inexperience causing him to press his whole body forward as he does. Their nipples brush. Sylvain keens, grabbing Felix's waist. "Good, good boy."

Felix whimpers and kisses Sylvain again, licking almost shyly into his mouth as he thrusts the length of his cock along Sylvain's slit. It slides between his lips, gliding easily through Sylvain's wetness. The heat of their cores together makes Sylvain jerk, his hips swiveling to try and get the head of Felix's cock inside even as his brain cries out at him to make it last longer. 

"So good, Felix," Sylvain says, his mouth running wildly. "Perfect boy - the best -" 

Felix shivers out a weak little moan into his mouth. "Sylvain - _hurts_." 

"What hurts, baby?" The head of Felix's cock catches on Sylvain's hole, and Felix convulses. 

"Yes, Sylvain, please!"

Saints above, Sylvain isn't strong enough for this. He smooths Felix's sweaty hair back from his forehead. "Put it in, Felix, that's right," he says wildly, spreading his legs wider and pulling Felix's hips forward. "Feels good?" 

Felix sobs. " _Please._ " His hips buck forward, and his cock slides home into Sylvain in one smooth glide. It's hardly big enough to stretch him, but Sylvain moans anyway, clutching Felix tight and nosing at the thin skin of his neck. 

"Just like that, Felix, perfect." Felix's mouth hangs open as he thrusts, hips rabbiting against Sylvain's and bracing himself against Sylvain's chest. 

His knee slips; breaking his rhythm; with a tiny snarl he tries to heave Sylvain's leg up again, but his fingers can't get purchase on Sylvain's sweaty skin.

"Here," Sylvain manages to get out. "Let me turn over." Felix's hands scrabble at his chest as Sylvain dislodges him, but when Sylvain turns over, planting himself on hands and knees, he grows quiet.

Sylvain smiles to himself. _Never fails_. Wantonly, he spreads his legs and folds himself down to his elbows, arching his back and presenting the glistening folds of his cunt for Felix's perusal.

A wordless cry from behind him as Felix pounces, grabbing Sylvain's hips and thrusting his cock between his legs.

"Oh Goddess," Sylvain gasps, hanging his head. Felix's cock is coated in his slick, and and Sylvain enjoys a few brief moments of being humped like a dog before he reaches behind him and guides Felix's cock into his hole. 

Felix whimpers and thrusts, baring his teeth. Sylvain rests his cheek against the pillow, moaning as Felix's taut, tight balls smack against his cunt. It only takes a few thrusts before Felix gives a choked groan, buries himself deep, and spends inside him, warmth splattering Sylvain's messy cunt.

"Saints and swords," Sylvain wheezes, reaching down and rubbing the small bud at the apex of his slit. "Felix - yes -" 

But then Felix pulls out, still panting, frowning down at his cock and Sylvain’s cunt. Sylvain whines and thumps his fist against the sheets, furiously working his nub.

"It's coming out." 

"'S because you don't have a knot yet, baby," Sylvain pants. "It's okay. Just - I've got to -" 

Felix's hand on his flank makes him jump, ruining his rhythm. But suddenly, there’s a tongue lapping tentatively at his pussy.

" _Felix!_ "

"Mm," Felix says, butting his nose up against it. Sylvain feels himself get wetter and sobs, giving up and resting his head on his arms. "Tastes nice."

"You can lick harder," Sylvain says desperately. "Like - like kissing, right?"

He muffles his howls in the bedcovers when Felix sucks gently on his lips, tonguing at his hole and rubbing his face against Sylvain's cunt, murmuring something about his scent. Sylvain's voice cracks as Felix slides a finger inside him and spreads his hole, poking his tongue deep for a taste and inhaling the rich, musky scent.

It's like that that Sylvain spends, wailing and shaking on Felix's tongue and finger. Felix is hard again when he finishes, squirming and wriggling as his knot swells up. Legs trembling, Sylvain eases him against the pillows and lowers his lush, sopping pussy down onto Felix's cock until his knot catches inside.

Felix does cry, then, clutching Sylvain's hips tightly as he spends. Sylvain hugs him back, petting his hair as Felix's hips jerk and stutter, pumping him full. Sylvain grinds out another orgasm just milking Felix's cock, and when they're both exhausted, Felix shyly beckons him closer and nuzzles his neck.

"Sylvain," he whispers. "Don't - don't leave." Sylvain's heart wrenches in his chest. 

"Of course, Felix," he promises, kissing his forehead, then his mouth. The kiss is gentle, soft and sweet. "Wouldn't dream of it."

**Author's Note:**

> When Felix re-emerges from the infirmary two weeks later, back to his normal self save for a bit of chest hair that won't grow back, he finds Sylvain and begrudgingly asks him to talk. 
> 
> What follows is a whole lot of talking and then a _whole lot more_ sex for the rest of their lives.
> 
> •°• °•° •°•
> 
> [RT this fic on Twitter!](https://twitter.com/JaneBuzJane/status/1258758781418328066?s=19)


End file.
